With obesity on the rise in the industrialized countries, the incidence of degenerative diseases such as cardiovascular disease, hypertension and diabetes is also rising at alarming rates. While obesity can be due to a combination of genetic, psychological, socioeconomic and cultural factors, a more straightforward, bottom-line explanation is that obesity is “caused” by an imbalance of energy intake as compared to energy expenditure. As humans continually become more aware of the health risks associated with obesity, more people are trying to live healthier lives, which typically includes eating healthier.
Much of the blame for the rise in obesity and disease has been focused on fats and oils. Although fats and oils are critical to a balanced diet, many people in the industrialized countries have a tendency to consume more than is needed. A major source of consumption of fats and oils is foods that have been fried or baked in cooking oil. These cooking oils absorb into the food and give it certain texture, color and palatable qualities to which people have become accustomed. Simply eliminating these cooking oils or fried foods from the diet often leaves people feeling unsatisfied, or decreases the flavor and palatability of foods to the consumer, so that motivation to eat such foods for a potential health benefit is short lived. So far, low fat oil substitutes have generally proven to be unsuccessful. The public does not seem to be willing to compromise taste for health. Healthier, more palatable edible oils may be the key to controlling the incidence of obesity and certain diseases.
U.S. Pat. No. 6,004,611 discloses an edible oil composition having unique nutritional benefits. The majority of this edible oil composition is diglycerides, of which the 1,3-diglycerides (comprising more than 40% of the oil) are considered to be the actual beneficial component. When edible oils of triglyceride nature are digested, they are broken up into fat components. The body packages the components into triglycerides, and transports them to the tissue while the liver handles the excess.
Triglycerides are stored in the adipose tissue until the body needs them for energy at a later time. However, the body does not package the digested components of 1,3-diglycerides as it does the triglycerides. Therefore, the components of 1–3-diglycerides are transported to the liver to be metabolized. In other patent publications from the same assignee (EP 0 307 154 B2, WO 99/09119) the inventors disclose a process for the preparation of this diglyceride (DG) oil. They disclose a process which includes splitting or partially splitting triglyceride oils to yield the corresponding fatty acids, followed by the separation and fractionation of these fatty acids, and then the selective enzymatic esterification of the fractionated acids with glycerol to make a DG oil rich in 1,3-diglycerides. The DG oil is further processed to attain the desired color and flavor. This patent teaches that a 1,3-specific enzyme is used for this esterification reaction to increase the content of 1,3-diglycerides. To maximize the positional specificity, the DG oil was also prepared from fatty acids and glycerol (the products of the fat splitting reaction of triglyceride (TG) oils).
The process disclosed in WO 99/09119 has several side effects that are labor intensive and expensive to overcome. During the fat splitting step, the triglyceride oil feedstock is subjected to high temperature and high pressure, which causes discoloration and contamination of the reaction products with high levels of trace metals and trans fatty acids. Also, glycerol is recovered as an aqueous solution and has to be distilled and cleaned in order to be used in subsequent esterification reactions. The fatty acids also have to be cleaned, either before esterification or after esterification, to be suitable for an edible application.
It has long been known that the positional isomers of partial glycerides, such as monoglycerides (MG) or diglycerides, reach an equilibrium composition at a certain ratio of the possible positional isomers. Thus, even though the process disclosed in WO 99/09119 achieves a DG oil with a high level of 1,3-diglyceride through the selective enzymatic esterification reaction, the final ratio of 1,3- to 1,2-diglycerides comes to equilibrium following esterification and storage of the product.